Is it too strong to allow a pc with alert feat to alert his friends?

Assume the following situation: The party has been surprised by an ambush. Every PC is surprised except PC Bob because he has the alert feat. Thanks to his high initiative bonus Bob gets to go first. He shouts “look out” to alert his party members of the imminent threat. The idea is that his party members are no longer surprised because he warned them.

While I think that this makes sense from a story telling perspective I am afraid this would be too strong as it allows one PC with the alert feat to give the “not surprised” part to other members of his party for pretty much free.

Is this allowed? Is there a RAW ruling or similar on this?

If not, do you have any experience with this situation and how did it play out in your games?